低谐波LCL滤波器的光伏并网逆变器的研究

发布时间：2018-04-20 09:38

本文选题：LCL滤波器 + 光伏并网逆变器　；参考：《安徽理工大学》2014年硕士论文

【摘要】：近年来,随着能源短缺与环境污染的加剧,发展清洁能源成了当今能源研究的热点。太阳能因为其用之不尽、取之不竭和无污染的特点受到了广泛关注。光伏发电也成了电力行业的一大热门课题。光伏并网发电系统是未来太阳能发电的主要形式。在光伏并网发电系统中,逆变环节是系统的重要组成部分。本文主要针对这个部分展开研究,主要研究内容如下：首先,介绍了光伏发电系统的几种基本结构,重点分析了光伏发电系统的核心部件—并网逆变器的结构、分类等。从中选取三相全桥逆变电路作为光伏并网逆变器。为获得高质量的并网电流,在三相全桥逆变器后端加上LCL滤波器作为后级滤波环节。LCL滤波器的滤波性能良好,但存在谐振问题,故参数的设计对系统稳定性的保持显得尤为重要。本文从等效总电感量、功率控制和谐振频率三个方面对滤波器的参数进行设计。LCL滤波器因其自身的优点,在大功率场合的应用越来越广泛,但其存在固有谐振点。为了解决这一问题,本文根据LCL滤波器的拓扑结构,分析其工作原理,从无源阻尼控制和有源阻尼控制两方面分析LCL型光伏并网逆变器的控制方案。通过采用不同位置的电流作为系统控制的反馈量,分析不同反馈量对系统稳定性的影响,本文提出一种新的并网逆变器控制策略——并网电流外环、电容电流内环的双闭环控制。建立其三相静止坐标系下的数学模型,求得其在两相旋转坐标系下的模型,通过解耦,实现d、q轴电流独立控制,实现电流双闭环控制,并采用SVPWM方式进行调制。然后在MATLAB/Simulink环境中搭建系统仿真模型,对LCL滤波器参数和控制策略的选取进行验证。仿真结果表明,基于并网电流外环、电容电流内环的双闭环控制能实现高功率因数跟踪电网,且系统能保持稳定,并且LCL滤波器能有效滤除电流高次谐波,提高并网电流质量,具有较大的理论和实践意义。最后对系统的硬件部分进行了设计,包括主电路设计、采样电路设计、保护电路设计及驱动电路设计。
[Abstract]:In recent years, with the increasing of energy shortage and environmental pollution, the development of clean energy has become the focus of energy research. Solar energy has been widely concerned because of its inexhaustible, inexhaustible and pollution-free characteristics. Photovoltaic power generation has also become a hot topic in the power industry. Photovoltaic grid-connected power generation system is the main form of solar power generation in the future. In photovoltaic grid-connected generation system, inverter is an important part of the system. This paper focuses on this part of the study, the main research content is as follows: Firstly, several basic structures of photovoltaic power generation system are introduced, and the structure and classification of grid-connected inverter, the core component of photovoltaic power generation system, are emphatically analyzed. Three-phase full-bridge inverter is selected as photovoltaic grid-connected inverter. In order to obtain high quality grid-connected current, the filter with LCL filter at the back end of three-phase full-bridge inverter has good filtering performance, but the resonance problem exists. So the design of parameters is very important to the stability of the system. In this paper, the parameters of the filter are designed from three aspects: equivalent total inductance, power control and resonant frequency. Because of its own advantages, the LCL filter is more and more widely used in high-power applications, but it has inherent resonance point. In order to solve this problem, according to the topology of LCL filter, this paper analyzes its working principle, and analyzes the control scheme of LCL photovoltaic grid-connected inverter from two aspects: passive damping control and active damping control. By using the current of different position as the feedback quantity of the system control, and analyzing the influence of the different feedback quantity on the stability of the system, a new control strategy of grid-connected inverter, the grid-connected current outer loop, is proposed in this paper. Double closed loop control of capacitor current inner loop. The mathematical model in the three-phase stationary coordinate system is established, and its model in the two-phase rotating coordinate system is obtained. By decoupling, the current of dq-axis is controlled independently and the current is controlled by double closed loop, and the modulation is carried out by using SVPWM mode. Then the system simulation model is built in MATLAB/Simulink environment to verify the selection of LCL filter parameters and control strategies. The simulation results show that the double closed-loop control of capacitive current inner loop based on grid-connected current outer loop can realize high power factor tracking power grid, and the system can maintain stability, and LCL filter can effectively filter high harmonic current and improve the quality of grid-connected current. It has great theoretical and practical significance. Finally, the hardware part of the system is designed, including the main circuit design, sampling circuit design, protection circuit design and drive circuit design.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

【参考文献】